Roller assembly for floating watercraft port

ABSTRACT

One example provides a roller assembly for conveying a watercraft on a floating drive-on watercraft port. The roller assembly includes an axle, a center roller disposed on the axle, and a pair of shoulder rollers disposed on the axle, one shoulder roller disposed on each side of the center roller, the center roller and each shoulder roller free to spin independently from one another about the axle. Each shoulder roller includes an outer sidewall facing away from the center roller, and an inner sidewall facing the roller, a diameter of the shoulder roller at the outer sidewall being greater than a diameter of the shoulder roller at the inner sidewall such that an outer circumferential surface of the shoulder roller is downwardly angled from the outer sidewall toward the center roller.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a non-provisional of U.S. Patent Application Ser.No. 63/073,709, filed Sep. 2, 2020, which is incorporated herein byreference.

BACKGROUND

Floating watercraft ports provide easy drive-on docking and out-of-waterstorage of watercraft, including personal watercraft and boats ofvarious hull-types. Such floating watercraft ports typically include arecessed cradle formed in an upper surface of the port, and a number ofrollers to receive and guide a hull of the watercraft along the cradleduring entry onto and exit from the floating port. As owners purchasedifferent watercraft, and watercraft hull designs change over time, itis advantageous for floating drive-on ports to be able to accommodatevarious hull sizes and shapes.

SUMMARY

One example provides a roller assembly for conveying a watercraft on afloating drive-on watercraft port. The roller assembly includes an axle,a center roller disposed on the axle, and a pair of shoulder rollersdisposed on the axle, one shoulder roller disposed on each side of thecenter roller, the center roller and each shoulder roller free to spinindependently from one another about the axle. Each shoulder rollerincludes an outer sidewall facing away from the center roller, and aninner sidewall facing the center roller, a diameter of the shoulderroller at the outer sidewall being greater than a diameter of theshoulder roller at the inner sidewall such that an outer circumferentialsurface of the shoulder roller is downwardly angled from the outersidewall toward the center roller.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of embodiments and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments andtogether with the description serve to explain principles ofembodiments. Other embodiments and many of the intended advantages ofembodiments will be readily appreciated as they become better understoodby reference to the following detailed description. The elements of thedrawings are not necessarily to scale relative to each other. Likereference numerals designate corresponding similar parts.

FIG. 1 is a perspective view of a floating watercraft port includingrollers, according to one example of the present disclosure.

FIG. 2 is a top view of a floating watercraft port including rollers,according to one example of the present disclosure.

FIG. 3 is a perspective view illustrating a base portion of a floatingwatercraft port including rollers, according to one example of thepresent disclosure.

FIG. 4 is a perspective view illustrating an entrance portion of afloating watercraft port including rollers, according to one example ofthe present disclosure.

FIG. 5 is a perspective view of a floating watercraft port includingrollers, according to one example of the present disclosure.

FIG. 6 is a perspective view of a wobble roller, according to oneexample.

FIG. 7 is a side view of a wobble roller, according to one example.

FIG. 8 is a perspective view of a wobble roller rim, according to oneexample.

FIG. 9 is a perspective view of a wobble roller assembly, according toone example.

FIG. 10 is a perspective cross-sectional view of a wobble rollerassembly, according to one example.

FIG. 11 is a cross-sectional view of a wobble roller hub, according toone example.

FIG. 12 is a cross-sectional view of a wobble roller assembly, accordingto one example.

FIG. 13 is a cross-sectional view of a wobble roller assembly, accordingto one example.

FIG. 14 is a cross sectional view of an alternative implementationcomprising a bushing that fits inside the hub that allows transversearticulation perpendicular to changing hull pitch. The bushing can bemanufactured in a way that a lubricant can be added to the moldedbushing that would otherwise interfere with adhesion from wheel hub toover-mold substrate.

FIG. 15 is a cross sectional view of an alternative implementationcomprising a gradual curved pitch to transfer weight load evenly at anyangle.

FIG. 16 is a cross sectional view of an alternative example of theovermold in which suspension holes have a gradual wall thickness changethe employs greater force to compress in “0” degrees and graduallyreduces force required to compress suspension holes towards the outeredge of the wheel.

FIG. 17 is a cross sectional view of an alternative example of theover-mold in which suspension holes have a one sided taper suspensionhole to gain less suspension travel on one side vs. other. In thisembodiment user can change wheel orientation around to accommodate atailored compression assembly.

FIG. 18 is a cross sectional view of an alternative example of theover-mold in which suspension holes have a symmetrical suspension holethat reduces weight needed to compress on both sides equally.

FIG. 19 is a cross sectional view of an alternative example of theover-mold in which a symmetrical tapered suspension hole allows forgreater force requirement in the middle and gradually needs less forcetoward outside edges to compress suspension holes.

FIGS. 20 and 21 are cross sectional views of an alternative embodimentof a hub bushing that snap fits inside the hub and allows forarticulation of the wobble wheel while still allowing up to 10 degreesof articulation. Said embodiment also allows bushing polymer to hingeradially while spinning. Embodiment can employ a low friction additivefor lower desired coefficient of friction. This is accomplished byeliminating the lubricant from interrupting the chemical bond ofcompatible hub and substrate materials. Such bushing materials thatcould be used to accomplish this would be a engineered polymer such asHytrel(PET), PEEK or Acetal(POM) all which are compatible with aninternal molded lubricant. This embodiment also allows axle pin to stayconcentric and supported with bushing during articulated rotation. Thisembodiment also will maintain a home position of 0 degrees untilarticulation force is applied and will return to home position afterwheel weight is eliminated.

FIG. 22 is a perspective view illustrating a bowtie roller, according toone example.

FIG. 23 is a side view illustrating a bowtie roller, according to oneexample.

FIGS. 24A and 24B are perspective views illustrating a rim of a shoulderroller, according to one example.

FIGS. 25A and 25B are perspective views illustrating a tire of ashoulder roller, according to one example.

FIG. 26A is a perspective view illustrating a rim of a center roller,according to one example.

FIG. 26B is a perspective view illustrating a tire of a center roller,according to one example.

FIG. 27 is a cross-sectional view generally illustrating portions of abowtie roller, according to one example.

DETAILED DESCRIPTION

In the following Detailed Description, reference is made to theaccompanying drawings, which form a part hereof, and in which is shownby way of illustration specific embodiments in which the invention maybe practiced. In this regard, directional terminology, such as “top,”“bottom,” “front,” “back,” “leading,” “trailing,” etc., is used withreference to the orientation of the Figure(s) being described. Becausecomponents of embodiments can be positioned in a number of differentorientations, the directional terminology is used for purposes ofillustration and is in no way limiting. It is to be understood thatother embodiments may be utilized and structural or logical changes maybe made without departing from the scope of the present invention. Thefollowing detailed description, therefore, is not to be taken in alimiting sense, and the scope of the present invention is defined by theappended claims.

It is to be understood that the features of the various exemplaryembodiments described herein may be combined with each other, unlessspecifically noted otherwise.

FIGS. 1 and 2 are perspective and top views, respectively, illustratingan example of a floating drive-on watercraft port 10 including rollersto assist in guiding a watercraft on/off and along watercraft port 10,in accordance with the present disclosure, such as wobble wheels 60 andbowtie rollers 70. The example watercraft port 10 includes a basesection 12, and an entrance, or tail, section 14, which are hingedtogether so that base section 12 and tail section 14 can pivot orarticulate relative to one another about an axis 16 to assiston/off-loading of a watercraft to/from port 10. In examples, basesection 12 and tail section 14 comprise rotationally molded shells ofhigh-density polyethylene filled with a marine-grade expandedpolystyrene (EPS) foam.

FIGS. 3 and 4 respectively illustrate perspective views of base section12 and tail section 14 when separated from one another. With referenceto FIG. 4, base section 12 includes a pair of hinge knuckles 15 a and 15b defining apertures 15 c. Hinge knuckles 15 a and 15 b insert intocorresponding hinge pockets in the bottom of tail section 14 (notillustrated), such that apertures 15 c align with correspondingapertures 16 a in tail section 14. Hinge pins (not illustrated) areinserted through apertures 15 c, 16 a to pivotally join tail section 14to base section 12.

With reference to FIGS. 1-4, in one example, a first end 18 of basesection 12 includes a pair of hinge knuckles 20 a, 20 b extendingtherefrom which enable base section 12 to be pivotally connected (e.g.,via pins) to another structure, such as a dock (e.g., a floating dock).An opposing second end 22 of base section 12 is non-linear in plan-viewand has an inset region 22 a that mates with a tongue-like extension 24a of a first end 24 of tail section 14. An opposing second end 26 oftail section 14 defines an inlet or mouth 28 for receiving and directinga bow of watercraft onto/off of floating watercraft port 10.

A top surface 30 of base section 12 and a top surface 32 of tail section14 together form a top surface 34 of watercraft port 10. A hulldepression 36 is molded into top surface 34 and is symmetrical about alongitudinal axis or centerline 38 of watercraft port 10, with hulldepression 36 being shaped to receive a hull of a watercraft. In oneexample, hull depression 36 includes a tapered bow region 40, anentrance region 42, and a center region 44 extending there between, andincludes port and starboard sidewalls 46 a and 46 b which curve upwardlyfrom a central channel 48 toward top surface 34. Port and starboardsidewall 46 a and 46 b of entrance region 42 are flared outwardlybetween port and starboard sides 49 a and 49 b of watercraft port 10,and downwardly towards a bottom surface 35 so as to form a funnel-likeramp which directs a watercraft hull upwardly along centerline 38 towardcenter region 44 of hull depression 36.

In one example, a number of recessed roller pockets 50 are formed inport and starboard sidewalls 49 a and 49 b of hull depression 36 alongcenterline 38 between bow region 40 and entrance region 42. In oneexample, opposing rows 52 a, 52 b and 54 a, 54 b of recessed rollerpockets 50 are symmetrically disposed along opposite sides of centralchannel 48 of hull depression 36 at different lateral distances (portand starboard) from centerline 38. In one example, a series of wobblewheels 60, which will be described in greater detail below, aresymmetrically mounted within roller pockets 50 on opposing sides ofenteral channel 48 to form guide tracks to engage and direct a boat hullalong centerline 36 while on/off-loading a watercraft to/from watercraftport 10. In one example, as will be described in greater detail below,an axle of wobble wheel 60 is mounted within axle sockets 51 a and 51 bon opposing sides of each roller pocket 50 (see FIG. 4), such that anaxis of rotation of wobble wheels 60 is orthogonal to central axis 36.

An entrance roller 70 is mounted within an entrance roller pocket 68disposed at a base of tapered mouth 28 of entrance region 42. In oneexample, as will be described in greater detail below, the entranceroller comprises a bowtie roller 70, in accordance with the presentdisclosure, which serves as a both as a shock absorber to lessen impactto both watercraft port 10 and a bow of a watercraft upon initialcontact during docking, and to direct the bow of a watercraft towardcenterline 38. In one example, as will be described in greater detailbelow, an axle of bowtie roller 70 is mounted within axle sockets 69 aand 69 b of roller pocket 68 (see FIG. 4), such that an axis of rotationof bowtie roller 70 is orthogonal to central axis 36.

In one example, as illustrated by FIGS. 1 and 2, wobble wheels 60 aremounted within roller pockets 50 of opposing rows 52 a and 52 b closestto centerline 36. In another example, as illustrated by the perspectiveview of watercraft port 10 of FIG. 5, a first portion of wobble wheels60 are mounted in roller pockets 50 of opposing rows 52 a and 52 b oftail section 14 closest to centerline 36, and a second portion of wobblewheels 60 are mounted in roller pockets 50 of opposing rows 54 and 54 bof base section 12 furthest away from centerline line 60. By mountingwobble wheels 60 in portions of both inner and outer rows 52 a/52 b and54 a/54 b of roller pockets 50, wobble wheels 60 mounted in tail section14 initially engage and guide the bow of a watercraft, which istypically narrower than other portion of the hull, onto watercraft port10 and along centerline 36, while wobble wheels 60 mounted in basesection 12 engage and guide wider portions of the watercraft hull as thewatercraft is further loaded onto watercraft port 10 while alsoproviding stability to a watercraft when docked.

FIGS. 6 and 7 respectively illustrate perspective and side views ofwobble wheel 60, in accordance with one example of the presentdisclosure. Wobble wheel 60 includes a rim 80 having a central hub 82defining a bore 84 configured to receive an axle (see FIGS. 9-13), anouter barrel 86, and a number of spokes 88 extending between central hub82 and in inner surface 86 a of outer barrel 86. A tire 90 is disposedabout the exterior surface of outer barrel 86. In one example, tire 90includes a plurality of through-holes 92 extending through tire 90between opposing sidewalls 94, where through-holes 92 assist tire 90 inabsorbing kinetic energy from a watercraft hull during docking byenabling tire 90 to better deflect relative to a solid tire. In oneexample, as illustrated, spokes 88 have a non-linear, curved shape whichenable spokes 88 and outer barrel 86 to more easily flex (to furtherabsorb kinetic energy) without fracturing (e.g., cracking) relative tostraight/linear spokes.

In one example, rim 80 and tire 90 each comprise single-piece, moldedcopolymer materials, such as thermoplastic elastomers (TPE) andthermoplastic rubbers (TPR), for example. In one example, tire 90 isover-molded onto rim 80. With reference to FIG. 8, which is aperspective view of rim 80, according to one example, outer surface 86 bof outer barrel 86 includes a number of depressions 87 formed thereinabout its circumference (e.g., scallop-like depressions) which assist insecuring tire 90 to rim 80 when over-molded thereon. In one example,tire 90 is formed with a copolymer material having a medium-softdurometer rating in a range from 55-75 so as to absorb shock and notdamage a watercraft hull, but with a low compression set so as toreturn-to-shape (and not have a “flat spot”) after supporting awatercraft for long periods of time.

With reference to FIG. 9, as described above, bore 84 of central hub 82receives an axle 98 which passes there through, about which wobble wheel60 is free to rotate. A longitudinal axis of axle 98 represents an axisof rotation 99 of wheel 60. Together, wobble wheel 60 and axle 98represent a wobble wheel assembly 100, where with opposing ends 98 a and98 b of axle 98 are seated within axle sockets 51 a and 51 b when wobblewheel assembly 100 is mounted within a recessed roller pocket 50. In oneexample, bushings or spacers 102 are disposed on axle 98 on both sidesof wobble wheel 60 so as to retain wheel 60 on axle 98 and to spacewheel 60 within roller pocket 50 so as to prevent contact with sidewallsthereof.

FIG. 10 is a perspective, cross-sectional view of wheel assembly 100 ofFIG. 9. In one example, as illustrated in greater detail below by FIG.11, central bore 84 is outwardly tapered so as to be flared or flutedsuch that a diameter of central bore 84 increases from a centraldiameter to an outer diameter at the openings to central bore 84 atopposing ends thereof.

FIG. 11 is a cross-sectional view illustrating central bore 84 ingreater detail. In one example, sidewall portions 110 a-110 d of bore 84are angled outwardly from a center circumference of bore 84 at atransverse centerline 112 thereof (which coincides with a transversecenterline of rim 80), such that a diameter of bore 84 increases from adiameter dC at center circumference of bore 84 at transverse centerline112, to a diameter dO at opposing openings 84 a and 84 b of bore 84. Inone example, the diameter of bore 84 increases linearly from diameter dCto diameter dO with the internal sidewall of bore 84, as illustrated at110 a-110 d, forming an angle, θ, with an axial centerline 114 of bore84 (which coincides with an axial centerline of rim 80, and with theaxis of rotation 99). In one example, values of 0 are in a range from 5to 10 degrees. In one example, θ has a value of 10 degrees.

The tapered shape of central bore 84 allows wobble wheel 60 to “wobble”or articulate from side-to-side on axle 98 as wheel 60 freely rotatesabout axle 98 when engaging a hull of a watercraft being driven onto oroff of watercraft port 10. By allowing wobble wheels 60 to rotate fromside-to-side, wobble wheels 60 are able to adjust to the position andsize of the hull, and are thereby better able to maintain alignment ofthe hull with centerline 36, and are better able to maintain a broadsurface contact with the hull so as to avoid damage thereto. In oneexample, as illustrated, the surface of tire 90 is crowned (has aradius) so as to maintain broad surface contact with a watercraft hullat different angles.

FIGS. 12 and 13 are cross-sectional views of wheel assembly 100respectively illustrating wobble wheel 60 tipped to the left and to theright. With sidewalls 110 a-110 d being at angle, θ, relative to axialcenterline 114 of bore 84 (see FIG. 11), the transverse axis 112 ofwobble wheel 60 is able to tilt at angle, θ, to the left of vertical 113(see FIG. 12), and at angle, θ, to the right of vertical 113 (see FIG.13), for a range of motion equal to 2×0. In one example, if angle, θ,has a value of 10-degrees, wobble wheel 60 has a range of motion of20-degrees (i.e., +/−10-degrees from vertical). By articulating to boththe left and right, wobble wheel assembly 100 can be universally mountedwithin roller pockets 50 in any direction on either side of centerline36. Although the range of angle, θ, of sidewalls 110 a-110 d of bore 84is described as being in a range from 5 to 10 degrees, other angles maybe employed. However, it is noted that rotation of wobble roller 60 willbe inhibited when tipped if angle, θ, is too large.

FIG. 14 is a cross sectional view of an alternative implementationcomprising a bushing that fits inside the hub that allows transversearticulation perpendicular to changing hull pitch. The bushing can bemanufactured in a way that a lubricant can be added to the moldedbushing that would otherwise interfere with adhesion from wheel hub toover-mold substrate.

FIG. 15 is a cross sectional view of an alternative implementationcomprising a gradual curved pitch to transfer weight load evenly at anyangle.

FIG. 16 is a cross sectional view of an alternative example of theovermold in which suspension holes have a gradual wall thickness changethe employs greater force to compress in “0” degrees and graduallyreduces force required to compress suspension holes towards the outeredge of the wheel.

FIG. 17 is a cross sectional view of an alternative example of theover-mold in which suspension holes have a one sided taper suspensionhole to gain less suspension travel on one side vs. other. In thisembodiment user can change wheel orientation around to accommodate atailored compression assembly.

FIG. 18 is a cross sectional view of an alternative example of theover-mold in which suspension holes have a symmetrical suspension holethat reduces weight needed to compress on both sides equally.

FIG. 19 is a cross sectional view of an alternative example of theover-mold in which a symmetrical tapered suspension hole allows forgreater force requirement in the middle and gradually needs less forcetoward outside edges to compress suspension holes.

FIGS. 20 and 21 are cross sectional views of an alternative embodimentof a hub bushing that snap fits inside the hub and allows forarticulation of the wobble wheel while still allowing up to 10 degreesof articulation. Said embodiment also allows bushing polymer to hingeradially while spinning. Embodiment can employ a low friction additivefor lower desired coefficient of friction. This is accomplished byeliminating the lubricant from interrupting the chemical bond ofcompatible hub and substrate materials. Such bushing materials thatcould be used to accomplish this would be a engineered polymer such asHytrel(PET), PEEK or Acetal(POM) all which are compatible with aninternal molded lubricant. This embodiment also allows axle pin to stayconcentric and supported with bushing during articulated rotation. Thisembodiment also will maintain a home position of 0 degrees untilarticulation force is applied and will return to home position afterwheel weight is eliminated.

FIGS. 22 and 23 respectively illustrate perspective and side views ofbowtie roller 70, according to one example of the present disclosure.Although illustrated primarily herein as being employed as an entranceroller, bowtie roller 70 may be used for other purposes and in otherlocations with floating watercraft ports. In the illustrated example,bowtie roller 70 includes a pair of shoulder rollers 120, illustrated asshoulder rollers 120 a and 120 b, and a center roller 140, with each ofthe rollers being disposed on a same axle 160, with each roller able tospin freely and independently from one another about axle 160. Eachshoulder roller 120 includes a rim 122 including a center hub 124defining a bore 126 to receive axle 160 (see FIGS. 24A and 24B below forfurther detail), and a tire 130 disposed on rim 122. In examples,bushings (not illustrated) may be disposed on axle 160 adjacent to eachshoulder roller 120 to maintain positions of shoulder rollers 120 andcenter roller 140 on axle 160.

With reference to FIG. 23, tire 130 of shoulder roller 120 includes aninner tire portion 132 and an outer tire portion 134, with shoulderroller 120 positioned on axle 160 such that inner tire portion 132 facescenter roller 140. In one example, a diameter of outer tire portion 134of tire 130 decreases from a diameter D1 at an outer sidewall 136 aopposite inner tire portion 132 to a diameter D2 where outer tireportion 134 transitions to inner tire portion 132, such that outer tireportion 134 has a first angle of depression, al, relative to an axis ofrotation 164 of bowtie roller 70 (which coincides with the longitudinalaxis of axle 160) from outer sidewall 136 a toward inner tire portion132. Similarly, a diameter of inner tire portion 132 decreases fromdiameter D2 at the transition with outer tire portion 134 to a diameterD3 at an inner sidewall 136 b, such that inner tire portion 132 has asecond angle of depression, α2, relative to the axis of rotation 164. Inone example, as illustrated, second angle of depression, α2, is greaterthan first angle of depression, al. In one example, the diameter ofcenter roller 140 matches the diameter, D3, at inner sidewall 136 b oftire 130.

FIGS. 24A and 24B are perspective views illustrating hub 122 of shoulderrollers 120, according to one example. Hub 122 includes a first hubportion 150, corresponding to outer tire portion 134, and a second hubportion 152 corresponding to inner tire portion 132 of tire 130. Firsthub portion 150 includes center hub 124 defining bore 126, an outerbarrel 154 having an inner surface 154 a and an outer surface 154 b, anda number of spokes 156 extending between center hub 124 and innersurface 154 a of outer barrel 154. In one example, outer surface 154 bincludes scallop-like depressions 158 to interlock with outer tireportion 134 of over-molded tire 130. Second hub portion 152 tapersdownward from first hub portion 150 and has an outer surface 170including a plurality of outwardly radiating ribs 172 to interlock innertire portion 132 of with over-molded tire 130.

FIGS. 25A and 25B are perspective views illustrating tire 130, accordingto one example. In one example, outer tire portion 134 includes a numberof tapered openings 180 extending partially through tire 130 from outersidewall 136 a. Openings 180 enable compression of otherwise solid tire130 (similar to through-holes 92 of wobble wheel 60) to provideabsorption of kinetic energy by shoulder rollers 120 when contacted by awatercraft hull. In one example, an outer surface of outer tire portion134 includes a tread 182 to shed water from shoulder rollers 120.

In one example, rim 122 and tire 130 of shoulder roller 120 eachcomprise single-piece, molded copolymer materials, such as thermoplasticelastomers (TPE) and thermoplastic rubbers (TPR), for example. In oneexample, tire 130 is over-molded onto previously molded rim 120. Withreference to FIGS. 24A and 24B, scallop-like depressions 158 and raisedribs 172 formed about the circumferential surface of hub 122 assist insecuring tire 130 to rim 122 when tire 130 is over-molded thereon. Inone example, tire 130 is formed with a copolymer material having amedium-soft durometer rating in a range from 55-75 so as to absorb shockand not damage a watercraft hull, but with a low compression set so asto return-to-shape (and not have a “flat spot”) after supporting awatercraft for long periods of time.

FIGS. 26A and 26B respectively illustrate perspective views of a rim 190and a tire 200 of center roller 140, according to one example. Rim 190includes an outer barrel 192 defining bore 126 through which axle 160passes. An outer surface 192 of barrel 192 includes a number ofdepressions 194 to assist in interlocking hub 190 with tire 200 which isover-molded thereon. A plurality of through-holes 202 extend throughtire 200 between opposing sidewall 204 a and 204 b to enable compressionof otherwise solid tire 200 (similar to through-holes 92 of wobble wheel60) to provide absorption of kinetic energy by center roller 140 whencontacted by a watercraft hull.

In one example, rim 190 and tire 200 of center roller 140 each comprisesingle-piece, molded copolymer materials, such as thermoplasticelastomers (TPE) and thermoplastic rubbers (TPR), for example. In oneexample, tire 200 is over-molded onto previously molded rim 190. Withreference to FIG. 26A, depressions 194 in outer surface 192 a of hub 190assist in securing tire 200 to rim 190 when tire 200 is over-moldedthereon. In one example, tire 200 is formed with a copolymer materialhaving a medium-soft durometer rating in a range from 55-75 so as toabsorb shock and not damage a watercraft hull, but with a lowcompression set so as to return-to-shape (and not have a “flat spot”)after supporting a watercraft for long periods of time.

With reference to FIGS. 1-2, bowtie roller 70 is positioned withinentrance roller pocket 68, with opposing ends 162 a and 162 b of axle160 being mounted within axle sockets 69 a and 69 b.

As described above, shoulder rollers 120 a, 120 b and center roller 140each spin independently about axle 160. When driving a watercraft ontowatercraft port 10, tapered mouth 28 of entrance section 14 directs abow of the watercraft to bowtie (entrance) roller 70. Upon initialcontact, openings 180 within tire 130 of shoulder rollers 120 a and 120b, through-holes 202 extending through tire 200 of center roller 140,and the elastic characteristics of the material from which tires 130 and200 are formed, absorb a portion of kinetic energy of the watercraftrather than transferring such kinetic energy into the watercraft port 10and the watercraft hull, thereby reducing a “jarring” effect of initialcontact. As the watercraft is driven onto watercraft port 10, theindependent spinning of each roller, and the downward angle of eachshoulder roller 120 a, 120 b toward center roller 140 cause thewatercraft hull to self-align with the longitudinal centerline 36 ofwatercraft port 10. Similarly, bowtie roller 70 functions to assist inmaintain central alignment of a watercraft hull when the watercraft isbeing driven off of watercraft port 10. As described above, centerrollers 140 of different widths may be employed to adjust an overallwidth of bowtie roller 170 to accommodate watercraft hulls of differentwidths.

FIG. 27 is a simplified cross-sectional view generally illustratingportions of a bowtie roller 70, according to one example of the presentdisclosure. According to the example of FIG. 27, inner tire portions 132of shoulder rollers 120 a and 120 b each include a circular extension196 extending from inner sidewall 136 b and forming a cylindrical rollerpocket 198 which is coaxial with bore 126. As illustrated, opposing endsof center roller 140 are disposed within cylindrical roller pockets 198of shoulder rollers 120 a and 120 b. Disposing opposing ends of centerroller 140 within roller pockets 198 prevents objects (including keelsof boat hulls and pontoons) from becoming wedged between the ends ofcenter roller 140 and shoulder rollers 120 a and 120 b.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat a variety of alternate and/or equivalent implementations may besubstituted for the specific embodiments shown and described hereinwithout departing from the scope of the present invention. Thisapplication is intended to cover any adaptations or variations of thespecific embodiments discussed herein. Therefore, it is intended thatthis invention be limited only by the claims and the equivalents thereof

What is claimed is:
 1. A roller assembly for conveying a watercraft on afloating drive-on watercraft port, comprising: an axle; a center rollerdisposed on the axle; and a pair of shoulder rollers disposed on theaxle, one shoulder roller disposed on each side of the center roller,the center roller and each shoulder roller free to spin independentlyfrom one another about the axle, each shoulder roller having: an outersidewall facing away from the center roller; and an inner sidewallfacing the roller, a diameter of the shoulder roller at the outersidewall being greater than a diameter of the shoulder roller at theouter sidewall such that an outer circumferential surface of theshoulder roller is downwardly angled from the outer sidewall toward thecenter roller.
 2. The roller assembly of claim 1, wherein each shoulderroller includes a cylindrical roller pocket on the inner sidewall whichis coaxial with the axle, wherein opposing ends of the center roller aredisposed within the cylindrical roller pockets of the pair of shoulderrollers.
 3. The roller assembly of claim 1, wherein the diameter at theinner sidewall is equal to a diameter of the center roller.
 4. Theroller assembly of claim 1, each shoulder roller having: an outerportion including the outer sidewall; and an inner portion including theinner sidewall, wherein an outer circumferential surface of the outerportion is angled downwardly from the outer sidewall to a transitionwith the inner potion at a first angle of depression from a lineparallel with a longitudinal axis of the axle, and the inner portion isangled downwardly from the transition with the outer portion to theinner sidewall at a second angle of depression form a line parallel withthe longitudinal axis of the axle, where the second angle is greaterthan the first angle.
 5. The roller assembly of claim 1, each shoulderroller including: a rim including a center hub defining a bore toreceive the axle; and a tire disposed about a circumferential surface ofthe rim, the tire including a plurality of openings extending partiallythrough the tire from the outer sidewall toward the inner sidewall. 6.The roller assembly of claim 5, wherein a portion of the tirecorresponding to the outer portion of each shoulder roller including atread configured to shed water.
 7. The roller assembly of claim 1, thecenter roller comprising: a rim defining a bore to receive the axle; anda tire disposed about a circumferential surface of the rim, the tireincluding a plurality of through-holes extending through the tirebetween opposing sidewalls.
 8. The roller assembly of claim 1, thecenter roller and each shoulder roller comprising molded copolymermaterials.
 9. A floating watercraft port comprising: at least onefloating dock section including: a first end; an opposing second end;and an upper surface including a hull depression formed thereinextending symmetrically about a longitudinal axis of the dock sectionbetween the first and second ends, and a wheel assembly disposed at theupper surface at the second end of the dock section for conveying awatercraft onto the dock section along the longitudinal axis, the wheelassembly comprising: an axle defining an axis of rotation orthogonal tothe longitudinal axis; a center roller disposed on the axle and centeredon the longitudinal axis; and a pair of shoulder rollers disposed on theaxle, one shoulder roller disposed on each side of the center roller,the center roller and each shoulder roller free to spin independentlyfrom one another about the axle, each shoulder roller having: an outersidewall facing away from the center roller; and an inner sidewallfacing the roller, a diameter of the shoulder roller at the outersidewall being greater than a diameter of the shoulder roller at theinner sidewall such that an outer circumferential surface of theshoulder roller is downwardly angled from the outer sidewall toward thecenter roller.
 10. The floating watercraft port of claim 9, including arecessed pocket extending into the upper surface, the wheel assemblydisposed within the pocket
 11. The floating watercraft port of claim 9,wherein the diameter at the inner sidewall is equal to a diameter of thecenter roller.
 12. The floating watercraft port of claim 9, eachshoulder roller comprising: an outer portion including the outersidewall; and an inner portion including the inner sidewall, wherein anouter circumferential surface of the outer portion is angled downwardlyfrom the outer sidewall to a transition with the inner potion at a firstangle of depression from a line parallel with a longitudinal axis of theaxle, and the inner portion is angled downwardly from the transitionwith the outer portion to the inner sidewall at a second angle ofdepression form a line parallel with the longitudinal axis of the axle,where the second angle is greater than the first angle.
 13. The floatingwatercraft port of claim 9, each shoulder roller comprising: a rimincluding a center hub defining a bore to receive the axle; and a tiredisposed about a circumferential surface of the rim, the tire includinga plurality of openings extending partially through the tire from theouter sidewall toward the inner sidewall.
 14. The floating watercraftport of claim 13, a portion of the tire corresponding to the outerportion of each shoulder roller including a tread configured to shedwater.
 15. The floating watercraft port of claim 9, the center rollercomprising: a rim defining a bore to receive the axle; and a tiredisposed about a circumferential surface of the rim, the tire includinga plurality of through-holes extending through the tire between opposingsidewalls.
 16. The roller assembly of claim 9, the center roller andeach shoulder roller comprising molded copolymer materials.
 17. A wheelassembly for conveying a watercraft on a floating drive-on watercraftport, comprising: an axle; a cylindrical center roller having a firstdiameter disposed on the axle; and a pair of shoulder rollers disposedon the axle at opposing ends of the center roller, each shoulder rollercomprising: an inner sidewall with a diameter equal to the firstdiameter disposed adjacent to the center roller; and an outer sidewallopposite the center roller with a second diameter greater than the firstdiameter such that an outer circumferential surface of the shoulderroller angles downwardly from the outer sidewall to the inner sidewall.18. The wheel assembly of claim 17, each shoulder roller comprising: aninner portion including the inner sidewall; and an outer portionincluding the outer sidewall; wherein from a reference line parallelwith a longitudinal axis of the axle, the outer circumferential surfaceof the outer portion has a first angle of depression from a lineparallel with a longitudinal axis of the axle, and the outercircumferential surface of the inner portion has a second angle ofdepression, the second angle greater than the first angle.
 19. The wheelassembly of claim 17, where each shoulder roller comprises: a rimdefining a bore through which the axle passes; and a tire disposed aboutthe rim, a circumferential surface of the tire forming the outercircumferential surface of the shoulder roller, wherein the tireincludes: a plurality openings extending partially through the tire fromthe outer sidewall toward the inner sidewall, the openings arrayed aboutan inner circumference of the tire between the rim and thecircumferential surface of the tire.
 20. The wheel assembly of claim 17,the center roller comprising: a rim defining a bore through which theaxle passes; and a tire disposed about the rim, a circumferentialsurface of the tire forming an outer circumferential surface of thecenter roller, wherein the tire includes: a plurality openings extendingthrough the tire between opposing sidewall surfaces.